Fiber Optics

Abstract

In this article, the principles of light guidance within a fiber and fiber fabrication methods are presented. Fiber‐optic sensors that are particularly useful for smart structures, and their applications, are also discussed. Fiber‐optic‐based communication depends on the availability of high quality low loss optical fibers. Operating wavelengths of fibers have been extended by controlling fiber attenuation and dispersion. The use of high purity starting materials and vapor deposition techniques allows the production of glass fibers having optical losses that approach the intrinsic loss of silica. Active optical fibers have been exploited to amplify light, thereby extending the range of transmission systems and increasing capacity. Erbium‐doped fibers are being used for signal amplification in fiber‐optic cable. Devices taking advantage of gratings written in optical fibers include filters and lasers. Applications of fiber‐optic sensors for smart structures fall into one of the four major categories: ( 1 ) sensors—monitoring such parameters as temperature, pressure, viscosity, degree of cure, and residual strain; ( 2 ) nondestructive testing—measuring acoustic signatures, changes in strain profiles, delamination, and other changes in the structural characteristics of fabricated parts; ( 3 ) condition and damage assessment systems—monitoring the overall condition of the structure; and ( 4 ) control—fiber‐optic smart structures may be used to support control systems.